#11: Stage 2 - Acceptable Evidence (Grading Scales)

Is there a difference between an assessment and a grade?

An assessment is any instrument that is able to measure or provide feedback on student achievement or performance. A grade is a recorded score that may be derived from an assessment or assessments.  An assessment need not be graded, but a grade, by name, is a point on an agreed upon scale of achievement.

Many formative and diagnostic assessments are not graded. Their primary purpose is informational feedback to both the student and the teacher. Most summative assessments -assessments of learning - are graded. They provide a measure of what the student knows and is able to do at the end of a learning period.

Here are two common grading scales, each having a number of ways they are used or expressed.

1. The straight points or percentage scale. Here, there are a certain number of possible points that may be earned and these points are awarded based on objective (or subjective) criteria. The most common scale is the percentage scale. All numerical scales may be converted to a percentage. The straight points scale is defended on the grounds that it is easy to understand, administer and defend. Conversely their critics say they can be unfair and arbitrary.
2. The level of achievement scale. Here, there a certain number of achievement levels that a student's work may be pegged against. Each level of achievement is described in terms of performance expectations within the context of a learning standard or objective. Levels of achievement are defended as clear, fair and objective. Opponents say they are subjective, inaccurate and difficulty to administer. 

The most common criticism of the percentage scale comes from its distribution of points within achievement levels. The F or failure range is accorded 60 points, while every other achievement level (from A to D) is accorded 10 points. The problem best reveals itself when two extreme grades are averaged. A grade of a zero when averaged with a grade of 100 gives a student a 50 - a failing grade. Proponents of levels of achievement recommend a 4-point scale with F (0); D (1); C (2); B (3) and A (4). They believe this evens out the scale and does not penalize a failure during the process of averaging. In the above extreme example, a 4 and 0 averages to a 2 (a C rather than a failing grade). They also argue that most schools use the 4-point scale when calculating GPA's.

A solution therefore may be to use the GPA scale as an assessment's grade. Teachers may still grade assignments using the percentage scale, but translate the grade to the GPA scale when they record it. For example anything below a 60% translates to a zero, while 60-69 translates to a 1; 70-79 translates to a 2; 80-89 translates to a 3; and 90-100 translates to a 4. This has the same effect as using the 4-point scale, but allows the traditional use of the percentage scale as well. This also has the same mathematical effect as recording a 50 as the lowest grade, but it does not come with the "baggage" of awarding free points for nothing.

While schools may see the logic and beauty of the 4-point scale, they may decide to keep using the more traditional percentage scale that the school community better understands. They may however also decide not to award a grade below a 50 in order to align the policy to the 4-point scale. They prefer this hybrid scale rather than the early application of the GPA scale as they may believe the point intervals (points between an 80 and 89 say, rather than just a 2) allow students a fairer and/or more accurate average at the end of the marking period.